1. Field of the Invention
The present invention relates to fluid powered actuator systems for operating a mechanism, such as an aircraft door, in an emergency; and more particularly to an apparatus which controls the discharge of pressurized fluid into an actuator that operates the mechanism.
2. Description of the Related Art
Commercial aircraft incorporate mechanisms for opening the doors of the passenger cabin in the event of an emergency. One known emergency door activating mechanism utilizes a piston/cylinder assembly that is operatively connected between the body of the aircraft and the door. A reservoir of gas, such as nitrogen, under high pressure is connected to the cylinder. When it is desired to open the door in an emergency situation, the pressurized nitrogen is released from the reservoir and applied to the cylinder thereby rapidly moving the piston and opening the door.
The prior systems which utilized a reservoir of pressurized gas suffered from the disadvantage that aging of the seals allowed the gas to leak from the reservoir over time. Thus, the system required frequent inspection and periodic maintenance to ensure that the high pressure gas was maintained in the reservoir for use in an emergency. This resulted in additional labor associated with monitoring and replacing the failed components. Furthermore, the aircraft had to be grounded if the emergency door activation system was not operational.
Although the emergency door activation system must rapidly operate the door to a fully open position, it should do so without damaging the door and other parts of the aircraft. It should be recognized that in many emergency situations, the aircraft is not severely damaged and can be repaired for subsequent use. As a consequence, activation of the emergency door system ought not result in further aircraft damage which results in additional repair costs. One prior solution involved a shock absorber hydraulic damping device, but that added extra weight to the aircraft which was disadvantageous.
It is therefore desirable to provide an apparatus for operating aircraft doors or other mechanical devices in an emergency, wherein the apparatus does not require frequent monitoring and operates in a manner which does not produce additional damage.